Experimental Study on the Anti-Cavitation Performance of Repair Materials and Joint-Filling Materials in the Adjacent Areas of Structural Joints on Overflow Surfaces

Dams, their spillways, and water conveyance structures are constantly exposed to high-velocity water flow, making them susceptible to cavitation and erosion that can compromise structural durability and operational safety. This study conducted ultrasonic and hydraulic cavitation tests on repair and joint-filling materials, evaluating their cavitation resistance based on indicators such as loss in mass, cavitation rate, cavitation resistance strength, macroscopic and microscopic morphological evolution, pitting rate, and damaged area. The results showed that, under ultrasonic cavitation testing, epoxy-based materials primarily exhibited pitting and localized spalling, polyurea materials primarily exhibited crack damage, and silicone materials developed localized cavitation pits. Among the materials that showed no significant mass loss in the ultrasonic cavitation test, epoxy mortar A had a cumulative cavitation area that was significantly larger than that of the other materials, at 43.2 mm2, while epoxy mastic A and epoxy mastic B had similar cumulative cavitation areas of approximately 5.7 mm2. In the hydraulic cavitation tests, all three repair materials exhibited a certain degree of cavitation resistance, but differences were observed in mass loss and failure modes. Damage to the repair materials frequently occurred at surface defects, edges, and weak interfaces of the test specimens, primarily manifesting as material fracture and spalling. Among them, epoxy mastic B exhibited the best cavitation resistance, with a mass loss reduced by 68.9% and 29.4% compared to epoxy mastic A and polyurea A, respectively. No significant surface damage was observed in the joint-filling materials; polyurethane A exhibited excellent cavitation resistance, with a 45% reduction in mass loss compared to silicone A. In summary, the repair and joint-filling materials examined in this study can all provide a certain degree of cavitation resistance while accommodating structural joint deformation and may serve as a reference for the repair of flow surfaces in hydraulic structures.